The box-office champion this past weekend was Captain America: Civil War, which raked in $181 million, in another proof of the infantilization of American culture. It seems that the
average mental age of Americans has plummeted to about 9, or perhaps at oldest, 11. Over several months, I have made notes that illustrate that an appalling proportion of popular entertainments for supposed adults in this country is infantile. Here is a very partial list of movies, television series, etc., that shows that the typical American is now a small child — or idiot, or, since these two categories are not mutually exclusive, both.
+Books and Movies:American Horror Story
Avengers: Age of Ultron
Captain America: The First Avenger
Captain America: Civil War
Harry Potter books and movies
Hobbit / Lord of the Rings books and moviesThe Huntsman movie franchise
Muppets movies
Superman movies
February 2016 movie, Gods of Egypt — with idiotic British accents for Egyptians+TV:Arrow
DC Legends of Tomorrow
The Flash
Galavant
Game of Thrones
Gotham
Grimm
Heroes, and Heroes Reborn
The Hunger Games
iZombie
Marvel's Agents of S.H.I.E.L.D.
Once Upon a Time
The Originals
Sanctuary (Canadian trash broadcast in the U.S.)Sleepy Hollow
Supergirl — lesbian-feminist trash, not just infantilism, that might get real women beaten to death, as men feel themselves endangered
Supernatural
Vampire Diaries
The Walking Dead+Past TV series (but some might still be shown in syndication):Batman
Dark Shadows
Hercules
Superman
True Blood
Xena, Warrior Princess+Cartoon shows, current or past, on OTA networks: The infantilization of American popular culture started a long time ago, but most strikingly in the Hanna-Barbera era from 1957 to about 2001. (See also Wikipedia articles "Prime time cartoon".) and Yogi Bear.

The Simpsons
Adult Swim and other offerings on the Cartoon NetworkAmerican Dad!
Animation Domination
Family Guy
Hanna-Barbera series (e.g., The Flintstones and The Jetsons)King of the Hill
Cleveland Show
Bob's Burgers+
I pass over movies intended for children, such as the Ice Age and Madagascar franchises, which adults attend only to accompany their children.
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I also pass over, but should not, the appalling amounts of time and money wasted on adults' playing professional sports  children's games  and being paid millions of dollars a year to do so. Many people who resent outrageous income inequality astoundingly do not begrudge the preposterous amounts that athletes make (not "earn") in their useless, worthless activities. Even worse, adults watch OTHER adults playing children's games. One might defend adults' playing athletic games themselves, for exercise, camaraderie, and a break from adult responsibilities, but watching OTHER people exercise? That is indefensible.
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Beyond these media issues, there are absurdly infantile usages that have almost entirely displaced adúlt usages, the most irritating being "a mom" and "a dad" in place of "a mother" or "a father". One even occasionally hears people in media refer to this past weekend's holiday as "Mom's Day"! "Mom" and "Dad" are forms of direct address, not nouns. Are the people in media who misuse these terms, only two or three years old? Are they retarded? It is not charming nor deliteful for adults to speak babytalk as a perfectly reasonable way for adults to communicate.
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It is for adults to demand adúlt behavior from adults. If a five-year-old says "your mom" or "his dad", s/he can be forgiven. But when a 35-year-old says such things, he should be upbraided and told to grow up. Let every adult in the United States tell the popular culture to grow up too.